African Americans and students with disabilities are suspended at “hugely disproportionate rates,” said leaders of the group, called the Discipline Disparities Research-to-Practice Collaborative. They also noted higher levels of suspension among Latinos and students who are lesbian, gay, bisexual and transgender.

“We need to pay close attention not only to the fact that suspension and expulsion are overused but that they affect certain groups much more than others,” said Russell J. Skiba, a professor at Indiana University and director of the collaborative.

The effort follows a broader push to rethink how schools punish student misconduct. In early January, Secretary of Education Arne Duncan and Attorney General Eric H. Holder Jr. jointly announced the first discipline guidelines for the nation’s schools. More recently, Maryland adopted sweeping new discipline regulations intended to keep more students in school and reduce racial disparities in suspension.

Skiba and others said they hoped the group’s work would build on the new federal effort by highlighting research on the problem and studies about alternate approaches.

In Virginia, they said, racial disparities narrowed in long-term suspension rates in schools that used threat assessment guidelines that provide procedures for examining the intent and risks associated with student misbehavior, according to research by Dewey Cornell of the University of Virginia and JustChildren, a child advocacy program of the Legal Aid Justice Center.

In Denver schools, research by Thalia Gonzalez, of Occidental College, showed success in restorative justice practices, which include building relationships and restoring the harm caused by aggression or conflict. Suspension rates decreased and disparities decreased, according to the discipline group.

In Indiana, Skiba’s research showed the importance of attitudes of principals and linked greater racial disparities to schools with principals that favor the use of suspension and expulsion. “Administrative leadership makes a substantial difference,” he said.

The discipline group cited work by Anne Gregory, of Rutgers University, which they said showed that a rigorous teacher training program intended to improve student engagement also had the added benefit of reducing disciplinary referrals and eliminating racial disparities in those referrals.

Racial disparities in discipline are sharply up in recent decades.

In the 1972-73 school year, suspension rates were 6 percent for whites and 12 percent for African Americans at the secondary school level. The most recent federal figures, for 2009-10, show rates of 7 percent for whites and 24 percent for African Americans in those grades, said researcher Daniel J. Losen, director of the Center for Civil Rights Remedies, at University of California, Los Angeles.

“While suspension rates have increased for all kids, the racial gap exploded,” Losen said. “It went from six points to 17 points, almost tripling.”

By comparison, 12 percent of Hispanics at the secondary level were suspended, he said.

A nationally representative population-based sample of adolescents indicates that lesbian, gay, bisexual and transgender youth are at greater risk of expulsion than their heterosexual peers, researchers said, citing a 2011 study.

For some student groups, the rates are markedly higher. For example, among middle and high school students, 36 percent of black males with disabilities were suspended at least once in 2009-10, Losen said.

Research shows that the stakes are high, experts said. Out-of-school suspensions are linked to academic disengagement, lower achievement and greater risks of school dropout and contact with the juvenile justice system, they said.

Skiba said a growing body of research shows that gaps in suspension rates are not result of disparate rates of misbehavior. The research, he said, shows many other possible factors at work in higher suspension rates: classroom management, diversity of teaching staff, administrative processes, characteristics of student enrollment, school climate.

The work of the group, funded by Atlantic Philanthropies and Open Society Foundations, was released at a congressional briefing Thursday, culminating efforts that began in 2011.

The group is hoping that the effort leads to improved tracking of suspensions and expulsions by race and other characteristics.

The group noted discipline successes in a number of school systems, including Baltimore, where the group said graduation rates had improved as school officials overhauled discipline and cut back substantially on out-of-school suspensions.

Researchers said they are also hoping that more school systems will consider new approaches and move toward using suspensions as a last resort. “It shows that with some resources and some intention, a lot can be done,” Losen said.